Hello! I've had for months now a dark spot on both my breasts where they meet as cleavage (the inside of my breasts; nowhere near my nipples). I think it has something to do with sweat or just my skin rubbing together because my breasts are big, but these small dark spots are very very very slightly dented in like craters. When I squeezed it to figure out what it was, a white substance of some kind emerges from it. I just want to know what's going on with my skin and if I should be concerned.